What is Antiplatelet Drug Toxicity?
As heart disease rates continue to rise globally, the use of medicines to prevent blood clotting, known as antiplatelet medications, is also increasing. These drugs are mostly used to reduce serious health risks linked to conditions like heart attacks, peripheral vascular disease, and stroke. All these medicines work by preventing blood cells from sticking together and forming a clot, which can help reduce the incidence of heart-related problems. However, these antiplatelet drugs mostly increase the risk of bleeding. In fact, people taking these medications have a 1.5 times higher chance of bleeding, and this risk increases if they are on additional blood-thinning drugs.
The negative effects of salicylates, a type of antiplatelet drug, are quite complex and therefore, they are only briefly discussed here. For a more in-depth understanding of salicylate toxicity, one can refer to a specific guide devoted to this topic. Today, we’ll mainly focus on comparing the effects of various blood-thinning medicines.
What Causes Antiplatelet Drug Toxicity?
The harm caused by anti-platelet drugs can be due to properly following the dosage recommendations or taking more than advised. Both situations can lead to bleeding. Looking at data from the National Poison Center in 2017, there were 2,831 instances of exposure to these kinds of drugs. Of these, 972 were accidental, and 48 were deliberate.
If someone takes too many anti-platelet drugs, it won’t significantly affect other parts of the body. However, it will increase the drug’s intended effect, which can then lead to various types of bleeding disorders.
Risk Factors and Frequency for Antiplatelet Drug Toxicity
In 2017, US poison centers reported 2831 cases of antiplatelet exposure, most of which were accidental and happened to individuals younger than 20. Out of these cases, 198 people received medical treatment. The report also stated that there were 16 medium-severity and five high-severity cases but no fatalities. Overdosing on antiplatelets raises the risk of significant bleeding, though this risk is lesser compared to overdosing on anticoagulants.
Signs and Symptoms of Antiplatelet Drug Toxicity
If you suspect someone might be experiencing antiplatelet toxicity, a thorough understanding of their medication use, and a complete physical exam can help decide the next steps, which may include lab tests and treatment. It will be helpful to know how much antiplatelet medication they took, how they took it, whether they combined it with other drugs, and why they took it.
Since uncontrollable bleeding is the main concern with antiplatelet toxicity, it’s a good idea to check for signs of bleeding. This would involve going over their medication history to figure out if there might be any interaction with antiplatelet drugs that could increase the risk of bleeding. If the person is noticeably bleeding, you should find out when the bleeding started, how long it’s been going on, and where it’s coming from.
A clinical check-up should also cover important health measures like heart rate, breathing rate, temperature, and blood pressure, and look for any signs of platelet dysfunction. These can include:
- Bleeding under the conjunctiva, the clear tissue covering the white part of the eye
- Bruising (ecchymosis)
- Small red spots on the skin (petechiae)
- Nosebleeds (epistaxis)
- Bleeding gums
- Blood in urine (hematuria)
- Bleeding in the stomach or intestines
If the person’s neurological examination isn’t normal, that might suggest bleeding inside the skull.
Testing for Antiplatelet Drug Toxicity
Keeping track of how well the blood platelets are working, whether it’s for managing a treatment to prevent blood clots or after a case of medication overdose, is tricky. Doctors sometimes use the ‘bleeding time’ test, which measures how fast your body can stop bleeding, but this test has many drawbacks. There are modern tests like ‘light transmittance aggregometry,’ but they are not available everywhere and have their issues.
Another test, called ‘thromboelastography’ (TEG), is becoming more commonly used. This test gives an overall picture of how well your body’s clotting process is working, but there’s conflicting information on how useful it is for people taking medication to prevent blood clotting.
When a patient comes in with bleeding, lab tests can be useful. These tests can include a complete blood count to check the number of platelets and the amount of a protein called hemoglobin. Tests can also be run to check how the platelets are working (like the bleeding time test and a platelet function test), and to see if there are any unusual features in the blood cells. If severe bleeding is happening, other tests, like ‘prothrombin time’ (PT), ‘activated partial thrombin time’ (APTT), and a cross-match of packed red blood cells may be helpful.
Treatment Options for Antiplatelet Drug Toxicity
At present, there are no specific antidotes for any of the antiplatelet medications we’ve talked about, and there are no universal reversal guidelines. Activated charcoal might be an option if the patient can safely drink liquids, and if they arrive soon after consumption, usually within the first one or two hours. The primary treatment should look to control any bleeding. If the patient experiences gastrointestinal bleeding, they could be treated with endoscopic evaluation and treatment depending on whether the position of the bleeding is at the beginning or end of the gastrointestinal tract.
If a patient comes to the hospital with severe bleeding related to antiplatelet medications, some treatment options would be platelet transfusions and a medication called desmopressin. But please note, there’s still not a lot of solid evidence to back up the use of desmopressin. Desmopressin works by increasing the levels of certain components in the blood known as factor VIII and Von Willebrand factor. These components help in the clotting process, which is different from the function of antiplatelet medications.
In severe bleeding cases, it might be necessary to resuscitate the patient with blood products like packed red blood cells and platelets. If there is a blood clotting disorder due to severe bleeding, plasma might also be required. For specific antiplatelet drugs known as GPIIb/IIIa inhibitors, stopping the medication will lead to the normalization of platelet function within two to three days for a drug called abciximab and within four to eight hours for the drugs eptifibatide and tirofiban.
What else can Antiplatelet Drug Toxicity be?
Patients taking antiplatelet therapy, which prevents blood clotting, may experience bleeding issues. What the doctors might suspect to be causing the bleeding will depend on where it’s happening. Bleeding might occur in different areas such as the digestive tract, urinary tract, brain, or other parts of the body. Each of these will have a unique list of possible causes.
Because of this, it’s fair for doctors to consider if the antiplatelet medication itself could be causing excessive bleeding. They would also typically review all other ongoing medications to rule out any possible interferences or side effects. If you’re experiencing any unusual bleeding while on antiplatelet treatment, it’s best to discuss this with your healthcare provider.
What to expect with Antiplatelet Drug Toxicity
The prognosis, or potential outcome, can differ greatly based on the location and severity of the bleeding. Normally, exposure to antithrombotic (blood-thinning) agents isn’t harmful. However, serious bleeding and even death can sometimes occur.
A report from the National Poison Data System in 2017 reported five significant health impact cases and no deaths out of 2831 exposures to these medications. Another study focusing on overdoses of antiplatelet drugs, which prevent blood clotting, reported 322 acute overdoses that resulted in 16 bleeding incidents, including two resulting in death.
Patients who experience bleeding in the brain while on blood-thinning medications typically have worse outcomes compared to those who are not on such medications.
Possible Complications When Diagnosed with Antiplatelet Drug Toxicity
Possible bleeding-related complications can include:
- Bleeding inside the skull
- Bleeding in the digestive system
- Bleeding behind the abdominal cavity
- Severe bleeding leading to shock
Preventing Antiplatelet Drug Toxicity
Patients who are taking antiplatelet medications should understand that these drugs can increase the risk of bleeding. It’s important that these medications are stored in a secure place, out of the reach of young children. If there are any questions or worries about potential side effects like toxicity, patients are urged to contact their local poison control center.
